In general, in a photolithographic technique for manufacturing semiconductor devices, a photoresist is applied to a semiconductor wafer or a FPD substrate and the like (hereinafter referred to as “wafer and the like”), a thus formed resist film is exposed in accordance with a predetermined circuit pattern, and the exposed pattern is developed so that a circuit pattern is formed in the resist film.
In such a photolithographic step, there is a possibility that bubbles of nitrogen gas or particles (foreign matters) might come to be mixed in a process liquid such as a resist liquid or a developing liquid to be supplied to a wafer, for some reason or other. When a process liquid containing bubbles or particles mixed therein is supplied to a wafer, application non-uniformity and/or defect may occur. Thus, a liquid processing apparatus for supplying a process liquid to a wafer is provided with a filter for filtrating bubbles and particles mixed in a process liquid.
As an apparatus for improving an efficiency in filtrating bubbles and particles mixed in a process liquid, there is known a process-liquid treating apparatus including a plurality of filters, which supplies a wafer with a process liquid having been filtrated through these filters. However, when a plurality of filters are provided, a liquid processing apparatus is enlarged and is needed to be largely modified.
There has been conventionally known a chemical-liquid supply system of a circulation filtration type, which includes: a first container configured to store a chemical liquid (process liquid); a second container configured to store a chemical liquid (process liquid); a first pump disposed in a first pipe connecting the first container and the second container and configured to send the chemical liquid stored in the first container to the second container; a first filter disposed in the first pipe; a second pipe connecting the first container and the second container; and a second pump disposed in the second pipe and configured to send the chemical liquid stored in the second container to the first container (see Patent Document 1).
In addition, as another liquid processing apparatus of a circulation filtration type including one filter, there is known a photoresist-application-liquid supply apparatus which includes: a buffer container of a photoresist application liquid (process liquid); a circulation and filtration apparatus that sucks a part of the photoresist application liquid from the buffer container to filtrate it by a filter, and then returns the filtrated photoresist application liquid to the buffer container; and a pipe through which the photoresist application liquid is sent from the buffer container or the circulation apparatus to a photoresist application apparatus (see Patent Document 2).